1. Field of the Invention
The present invention relates to an isolated polypeptide having protease activity and being homologous to Nocardiopsis proteases, as well as isolated nucleic acid sequences encoding it. The invention furthermore relates to nucleic acid constructs, vectors, and host cells, including transgenic plants and non-human animals, comprising these nucleic acid sequences, as well as methods for producing and using the protease, in particular within animal feed, for example in fish feed.
The protease of the invention is thermostable, and characteristic structural features of relevance for the thermostability of proteases of peptidase family S2A or S1E are disclosed.
The protease of the invention furthermore effectively degrades the soybean Bowman-Birk inhibitor, as well as other anti-nutritional factors such as soybean agglutinin, and the Kunitz trypsin inhibitor, and also isolated soy storage proteins such as, glycinin and beta-conglycinin.
2. Description of Related Art
Proteases derived from Nocardiopsis sp. NRRL 18262 and Nocardiopsis dassonvillei NRRL 18133 are disclosed in WO 88/03947. The DNA and amino acid sequences of the protease derived from Nocardiopsis sp. NRRL 18262 are shown in DK application no. 1996 00013. WO 01/58276 discloses the use in animal feed of acid-stable proteases related to the protease derived from Nocardiopsis sp. NRRL 18262, as well as a protease derived from Nocardiopsis alba DSM 14010. These proteases, however, are not thermostable.
JP 2-255081-A discloses a protease derived from Nocardiopsis sp. strain OPC-210 (FERM P-10508), however without sequence information. The strain is no longer available, as the deposit was withdrawn.
DD 20043218 discloses a proteolytic preparation derived from Nocardiopsis dassonvillei strain ZIMET 43647, however without sequence information. The strain appears to be no longer available.
JP 2003284571-A, published after the first filing date of the present invention, discloses the amino acid sequence and the corresponding DNA sequence of a protease derived from Nocardiopsis sp. TOA-1 (FERM P-18676). The sequence has been entered in GENESEQP with no. ADF43564. 
Thermostable proteases are described in the prior art, for example a protease from Thermomonospora fusca YX is described by Lao and Wilson in Appl. Environ. Microbiol. 62:4256–4259 (1996), and the sequence was filed in the public databases as sptrembl—086984. However, this protease is not homologous to Nocardiopsis proteases, as the percentage identity to the proteases of the invention is below 60%.
It is an object of the present invention to provide thermostable proteases that are homologous to Nocardiopsis proteases, in particular with a potential for use in animal feed and/or detergents.